UINavigationController，如何在第二级viewController中隐藏tabbar然后在第三级viewController中显示tabbar

Question

这里是我的一段代码，但这样，当我推动第三级视图控制器时，tabbar不会显示。

//at first level 
SecondLevelViewController *_2vc = [[SecondLevelViewController alloc]initWithNibName:@"SecondLevelViewController" bundle:nil]; 
    _2vc.hidesBottomBarWhenPushed = YES; 
    [self.navigationController pushViewController:_2vc animated:YES]; 

//at second level 
ThirdLevelViewController *_3vc = [[ThirdLevelViewController alloc]initWithNibName:@"ThirdLevelViewController" bundle:nil]; 
    _3vc.hidesBottomBarWhenPushed = NO; 
    [self.navigationController pushViewController:_3vc animated:YES]; 

Answer 1

相反，当你初始化视图控制器设置hidesBottomBarWhenPushed的值，则应改为处理中的隐藏机制 - （空）viewWillAppear中：（BOOL）在视图控制器，而不是动画。

这种实现的一个例子是：

在SecondLevelViewController.m

-(void)viewWillAppear:(BOOL)animated 
{ 
    [_bottomBar setHidden:YES]; 
} 

在ThirdLevelViewController.m

-(void)viewWillAppear:(BOOL)animated 
{ 
    [_bottomBar setHidden:NO]; 
} 

Answer 2

// Load the view 
    AddViewController *aController = [[AddViewController alloc] init]; 

    // Set the view title 
    aController.title = @"Add View"; 

    // hide tabbar 
    aController.hidesBottomBarWhenPushed = YES; 

    // add it to stack. 
    [[self navigationController] pushViewController:aController animated:YES]; 

-(void)viewWillAppear: (BOOL)animated 
{ 
    [super viewWillAppear:animated]; 
    [self.tabBarController.tabBar setHidden:YES]; 
} 

-(void)viewWillDisappear: (BOOL)animated 
{ 
    [super viewWillDisappear:animated]; 
    [self.tabBarController.tabBar setHidden:NO]; 
}